critical distance between adjacent mid-rise and high-rise structures considering structure- soil- structure interaction effects

Adjacent structures affect seismic response of each other through connecting soil. regarding population growth and urban structures density, the cross interaction of adjacent structures, well-known as structure-soil-structure interaction (sssi), has received attentions in recent decades. soil-structure interaction (ssi) studies showed that, as a general trend,possibility of unexpected damage is decreased by introducing base flexibility in seismic structural design. in these studies,it appeared that both dynamic properties such as dynamic damping and stiffness, called as dynamic impedance, as well asfoundation input motion (fim), of an isolated structure, change by the ssi effects. moreover, the structure has influence on seismic motion of its surroundings, up to a distance of ten times the foundation length (gueguen et al., 2002). similarly, if a structure is constructed near the said structure, the nearby motion will change additionally. thus the structures have influence on dynamic properties and input motion of each other. gueguen et al. (2002) has shown that the effect of soilstructure interaction on nearby motion decreases as the distance increases. in contrast, finding critical distance between adjacent structures is not as simple as the case of the ssi because of the complexity of the sssi. on the other hand, since adjacent structures have strong effects on each other, both favorable and unfavorable, study of the critical distance seemsto be necessary.